Atomic layer deposition apparatus

ABSTRACT

A method and apparatus for atomic layer deposition (ALD) is described. The apparatus comprises a deposition chamber and a wafer support. The deposition chamber is divided into two or more deposition regions that are integrally connected one to another. The wafer support is movable between the two or more interconnected deposition regions within the deposition chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/646,706, filed Dec. 23, 2009, now U.S. Pat. No. 7,860,597 which is acontinuation of U.S. patent application Ser. No. 11/423,535, filed Jun.12, 2006, now issued as U.S. Pat. No. 7,660,644, which is a continuationof U.S. patent application Ser. No. 09/917,842, filed Jul. 27, 2001, nowissued as U.S. Pat. No. 7,085,616, which are hereby incorporated byreference in their entireties. Benefit of priority to the aforementionedapplications is claimed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to integrated circuit processing equipmentand, more particularly to atomic layer deposition (ALD) equipment.

2. Description of the Background Art

Semiconductor wafer processing systems that perform atomic layerdeposition (ALD) are used to form material layers on high aspect ratiostructures. Referring to FIG. 1, ALD systems typically comprise adeposition chamber 10, a gas supply system 12, and a gas exhaust system14. The deposition chamber includes a pedestal 11 that is used tosupport a substrate 13 such as a semiconductor wafer. The gas supplysystem 12 is used to provide reaction gases to the deposition chamber10, and the gas exhaust system 14 is used to remove reaction gases fromthe deposition chamber 10.

In ALD processes, a material layer is formed on a substrate bysequentially chemisorbing alternating monolayers of two or morecompounds thereon. Each of the alternating monolayers is chemisorbedonto the substrate by providing a different deposition gas to thechamber that comprises one of the two or more compounds used to form thematerial layer. After each monolayer is chemisorbed on the substrate, apurge gas is introduced into the deposition chamber to flush thedeposition gas therefrom.

Since each of the alternating monolayers of the two or more compoundsused to form the material layer is chemisorbed onto the substrate byproviding a different deposition gas to the chamber followed by a purgegas, atomic layer deposition (ALD) processes are time consuming. Assuch, integrated circuit fabrication using ALD processes are costly dueto decreased wafer throughput.

Therefore, a need exists in the art for atomic layer deposition (ALD)systems for integrated circuit fabrication.

SUMMARY OF THE INVENTION

A method and apparatus for atomic layer deposition (ALD) is described.The apparatus comprises a deposition chamber and a wafer support. Thedeposition chamber is divided into two or more deposition regions thatare integrally connected one to another. The wafer support is movablebetween the two or more interconnected deposition regions within thedeposition chamber.

The atomic layer deposition (ALD) apparatus is compatible withintegrated circuit fabrication processes. In one integrated circuitfabrication process, a substrate is positioned on a wafer support in anALD apparatus comprising two or more integrally connected depositionregions. The wafer support with the substrate thereon is then moved intoa first one of the integrally connected deposition regions wherein afirst monolayer of a first compound is formed on the surface thereof.After the first monolayer of the first compound of formed on the surfaceof the substrate the wafer support is moved to a second one of theintegrally connected deposition regions wherein a second monolayer of asecond compound is formed on the first monolayer of the first compound.Thereafter, alternate monolayers of the first and second compounds aredeposited one over the other by moving the wafer support with thesubstrate thereon between the two or more integrally connecteddeposition regions until a material layer having a desired thickness isformed on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 is a schematic diagram of a prior art atomic layer deposition(ALD) apparatus;

FIG. 2 is a schematic diagram of an atomic layer deposition (ALD)apparatus that can be used for the practice of embodiments describedherein;

FIG. 3 is a flow diagram of a process sequence for the atomic layerdeposition (ALD) apparatus of FIG. 2; and

FIG. 4 is a schematic diagram of a second embodiment of an atomic layerdeposition (ALD) apparatus that can be used for the practice ofembodiments described herein.

DETAILED DESCRIPTION

FIG. 2 is perspective view of an atomic layer deposition (ALD) apparatus100 that can be used to form a material layer on a semiconductorsubstrate in accordance with embodiments described herein. The ALDapparatus 100 comprises a deposition chamber 105, a gas panel 130, acontrol unit 110, along with other hardware components such as powersupplies 106 and vacuum pumps 102.

The deposition chamber 105 comprises two or more deposition regions 200,300 that are integrally connected to each other. In FIG. 2 the two ormore deposition regions 200, 300 are configured as one above the otherin a vertical arrangement, however it is contemplated that the two ormore deposition regions may also be configured in a side by sidehorizontal arrangement (not shown).

The two or more deposition regions 200, 300 are integrally connected oneto another with an aperture 250. The aperture 250 is of a sufficientsize to permit the passage therethrough of a wafer support 150 having asubstrate thereon.

The aperture 250 is optionally sealed. The aperture is sealed tominimize the intermixing of deposition gases within the two or moredeposition regions 200, 300. Physical and/or pressure differences may beused.

Alternatively, an inert gas flow may be used to minimize the intermixingof deposition gases at the aperture 250 between the two or moredeposition regions 200, 300. The inert gas flow provides a laminar flowaround the area of the aperture 250. The inert gas flow is providedaround the area of the aperture 250 through orifices (not shown).

The process chamber 105 houses a wafer support 150, which is used tosupport a substrate such as a semiconductor wafer 190. The wafer support150 is moveable inside the chamber 105 between the integrally connecteddeposition regions 200, 300 using a displacement mechanism (not shown).

Depending on the specific process, the semiconductor wafer 190 can beheated to some desired temperature prior to material layer deposition.For example, wafer support 150 may be heated by an embedded heaterelement 170. The wafer support 150 may be resistively heated by applyingan electric current from an AC power supply 106 to the heater element170. The wafer 190 is, in turn, heated by the wafer support 190.

A temperature sensor 172, such as a thermocouple, may also be embeddedin the wafer support 150 to monitor the temperature of the support in aconventional manner. The measured temperature can be used in a feedbackloop to control the power supplied to the heater element 170, such thatthe wafer temperature can be maintained or controlled at a desiredtemperature which is suitable for the particular process application.The pedestal may optionally be heated using radiant heat (not shown).

A vacuum pump 102 is used to evacuate each of the deposition regions200, 300 of the process chamber 105 and to maintain the proper gas flowsand pressure inside the chamber 105. Orifices 120 provide process gasesto each of the one or more deposition regions 200, 300. Each orifice 120is connected to a gas panel 130 via a gas line 125, which controls andsupplies various gases used in different steps of the depositionsequence.

Proper control and regulation of the gas flows through the gas panel 130is performed by mass flow controllers (not shown) and the control unit110. Illustratively, the control unit 110 comprises a central processingunit (CPU) 113, as well as support circuitry 114, and memoriescontaining associated control software 116. The control unit 110 isresponsible for automated control of the numerous steps required forwafer processing—such as movement of the wafer support, gas flowcontrol, temperature control, chamber evacuation, and other steps.Bi-directional communications between the control unit 110 and thevarious components of the ALD 100 are handled through numerous signalcables collectively referred to as signal buses 118, some of which areillustrated in FIG. 2.

The central processing unit (CPU) 113 may be one of any form of generalpurpose computer processor that can be used in an industrial setting forcontrolling process chambers as well as sub-processors. The computer mayuse any suitable memory, such as random access memory, read only memory,floppy disk drive, hard drive, or any other form of digital storage,local or remote. Various support circuits may be coupled to the CPU forsupporting the processor in a conventional manner. Process sequenceroutines as required may be stored in the memory or executed by a secondCPU that is remotely located.

The process sequence routines are executed after the substrate 190 ispositioned on the wafer support 150. The process sequence routines, whenexecuted, transform the general purpose computer into a specific processcomputer that controls the chamber operation so that the depositionprocess is performed. Alternatively, the chamber operation may becontrolled using remotely located hardware, as an application specificintegrated circuit or other type of hardware implementation, or acombination of software and hardware.

Referring to FIG. 3, the ALD process sequence begins when asemiconductor wafer is positioned on the wafer support in one of the twoor more deposition regions 200, 300 of the deposition chamber 105, asindicated in step 350.

After the semiconductor wafer is positioned on the wafer support, adeposition gas is provided to each of the two or more deposition regions200, 300, as indicated in step 360 of FIG. 3. A different deposition gasis provided to each of the two or more deposition regions 200, 300. Thedeposition gases may each be provided using a continuous flow, oroptionally using a pulsed flow.

Thereafter as indicated in step 370 of FIG. 3, alternating monolayers ofeach deposition gas are chemisorbed onto the surface of thesemiconductor wafer to form a material layer having a desired thicknessthereon. Each monolayer is chemisorbed onto the surface of thesemiconductor wafer as the wafer support is alternately moved betweenthe two or more deposition regions through aperture 250.

Although embodiments described herein refer mainly to an atomic layerdeposition chamber having two deposition regions, those skilled in theart will appreciate that, as described, embodiments of the presentinvention will also encompass deposition chambers having more than twodeposition regions. For example, FIG. 4 is a schematic diagram of an ALDapparatus in which a wafer support is capable of movement between morethan two positions (Position 1, Position 2 and Position 3) to transportwafers between a plurality of deposition regions within the chamber.Thus while the foregoing is directed to the preferred embodiment of thepresent invention, other and further embodiments of the invention may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims which follow.

1. A method of depositing a material layer on a substrate comprising:(a) positioning a substrate on a wafer support in a deposition chambercomprising a first deposition region and a second deposition region,wherein the first and second deposition regions are integrally connectedto one another, and wherein the wafer support is movable between thefirst and second deposition regions; (b) pulsing a first deposition gasinto the first deposition region and pulsing a second deposition gasinto the second deposition region; (c) moving the wafer support with thesubstrate thereon into the first deposition region wherein a firstmonolayer of the first deposition gas is chemisorbed onto the surface ofthe substrate; (d) moving the wafer support with the substrate thereoninto the second deposition region wherein a first monolayer of thesecond deposition gas is chemisorbed on the first monolayer of the firstdeposition gas; and (e) repeating steps (c) and (d) until a materiallayer having a desired thickness is achieved.
 2. The method of claim 1,wherein step (c) further comprises: moving the substrate supportvertically.
 3. The method of claim 1, wherein step (c) furthercomprises: moving the substrate support horizontally.
 4. The method ofclaim 1 further comprising: flowing an inert gas between the depositionregions.
 5. A method of depositing a material layer on a substratecomprising: exposing a substrate positioned in a first deposition regionof a deposition chamber to a first deposition gas, a first monolayer ofthe first deposition gas is chemisorbed onto the surface of thesubstrate; moving the substrate having the first monolayer chemisorbedthereon from the first deposition region to a second deposition regionof the deposition chamber; and exposing the substrate positioned in thesecond deposition region of the deposition chamber to a seconddeposition gas, wherein a first monolayer of the second deposition gasis chemisorbed on the first monolayer of the first deposition gas,wherein the first and second deposition gases are pulsed into thedeposition chamber while flowing an inert gas between the first andsecond deposition regions.
 6. The method of claim 5 further comprising:cyclically exposing the substrate to the first and the second depositiongases until a material layer having a desired thickness is formed. 7.The method of claim 6 wherein cyclically exposing the substrate to thefirst and the second deposition gases further comprises: cyclicallymoving the substrate between the first deposition region for exposure tothe first deposition gas and the second deposition region for exposureto the second deposition gas.
 8. The method of claim 5, wherein movingthe substrate from the first deposition region to the second depositionregion further comprises: moving the substrate vertically.
 9. The methodof claim 5, wherein moving the substrate from the first depositionregion to the second deposition region further comprises: moving thesubstrate horizontally.
 10. The method of claim 5 further comprising:regulating pressure within the first deposition region independentlyfrom pressure regulated within the second deposition region.
 11. Themethod of claim 5 further comprising: proving laminar flow of gas aroundan aperture separating the first and second deposition regions.
 12. Themethod of claim 5, wherein moving the substrate from the firstdeposition region to the second deposition region further comprises:passing the substrate through a sealable aperture separating the firstand second deposition regions.
 13. The method of claim 5, wherein movingthe substrate from the first deposition region to the second depositionregion further comprises: moving a substrate support having thesubstrate disposed thereon from the first deposition region to thesecond deposition region.
 14. The method of claim 13, wherein moving thesubstrate from the first deposition region to the second depositionregion further comprises: moving a substrate support having thesubstrate disposed thereon through a sealable aperture separating thefirst and second deposition regions.
 15. The method of claim 13, whereinmoving the substrate from the first deposition region to the seconddeposition region further comprises: moving a substrate support havingthe substrate disposed thereon through a laminar flow of inert gas.